The Gold SMG is a new weapon in The Ballad of Gay Tony. It appears as gold-plated Mini Uzi. Yusuf Amir has a Gold SMG and is occasionally seen walking around with it.
It has the same stopping power, accuracy and sound as the Micro Uzi, and is, basically, a stumpier replacement. However, the rate of fire is different, as it fires much faster than the Micro Uzi. It has a 30-round magazine, rather than the Micro Uzi's 50 round magazine.
Because it is a much bigger than the Micro Uzi (and the fact that the gold plating is relativily heavy), Luis and the Multiplayer Character holds it with two hands, firing from the hip.
This gun, while being similar to the Uzi from GTA 4 and TLAD, has such an astounding rate of fire that it is the best gun in the game for drive bys and is not bad for ground warfare.

Artwork of Yusuf holding his Gold SMG.

Obtaining

After completing Yusuf Amir's final mission, he will award you with his car and the Uzi in the glove compartment.